Magnetic control device



Feb. 3, 1948. 1.. 1.. CUNNINGHAM MAGNETIC CONTROL DEVICE Filed April 13,1943 2 Sheets-Sheet 1 5 b we,

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Feb. 3, 194a. L. 1.. CUNNINGHAM 2,435,425

MAGNETIC CONTROL DEVICE y Filed April 15, 1945 2 sneetsfsnet 2 17 .5-IPA e9 4 I Zh'wcntor:

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Patented Feb. 3, 1948 UNITED STATES PATENT OFFICE MAGNETIC CONTROLDEVICE Lewis I. Cunningham, Los Angeles, Calif., as-' signor to GeneralControls 00., Glendale, Caiit, a corporation of California ApplicationApril 13, 1943, Serial No. 482,880 6 Claims. (01. 175-330) My presentinvention relates to magnetic control devices of the type which includesan armature movable to operate control means such as electricalcontacts, pilot valves, or the like. More particularly, the inventionrelates to such devices wherein a permanentmagnet is provided fornormally. holding the armature in attracted position, and having meansmovable into the field of the magnet for so shunting the flux thereofthat the armature is released.

An object of this invention is to provide a control device, of thecharacter described, wherein the magnet is of U-shape and the shuntingmeans is movable to a position between the side arms of the magnet, oradjacent the polar ends thereof.

Another object is to provide a device, of the character described in thepreceding object, wherein the armature is disposed in a planesubstantially parallel to that of the arms of the magnet so that acompact structure is formed.

Another object is to provide the U-shaped magnet with means which extendirom the polar ends of the magnet, in a direction at right-angles to theplane of the arms thereof, to form pole faces in a plane parallel tothat of the arms.

Another object is to provide the control device with an additionalU-shaped magnet which is arranged with its polar ends adjacent, andopposed to, the polar ends of the other magnet; thereby minimizing theleakage flux of the magnets, and permitting the shunting means to besymmetrically arranged between the polar ends of the magnets.

'A still further object is to provide, in the application of theabove-described control device to a fluid control valve, meansconnecting the shunting means to the closure member of the valve, andmeans interposed between the shunting means and the magnet for shieldingthe control device from the fluid controlled by the valve.

Other objects and advantages of the invention will be found in thedescription, the drawing, and

the claims; and, for full understanding of the invention, reference maybe had to the following detailed description and accompanying drawing,wherein:

Figure l is a longitudinal sectional view of a fluid control valve whichincludes, at its upper end, a magnetic control device embodying myinvention;

Figure 2 is a transverse section taken along the line 2-2 of Fig. 1;

Figure 3 is a fragmentary longitudinal section taken along the line 3-3of Fig. 2;

Figure 4 is a view, in perspective, of the magnetic control device shownin Figs. 1-3; and

Figures 5, 6 and 7 are diagrammatic views of typical control systemswhich include the mag- .netic device.

Referring first to Figs. 1-4 of the drawing, the

2 numeral ll indicates a valve casing having a ported partition l2providing a valve seat I] with which a closure member I4 cooperates.Mounted on the apertured top wall of the casing is an electromagneticoperator comprising a hollow cylindrical core ii, an annular coilwinding I8, and a reciprocable plunger I! which is connected by a stem18 to the closure member I. On the top of the core I! is a disk-shapedbase IQ, of insulating material, which supports the magnetic controldevice of the invention. The base is mounted on the core by means of apair of screws 20, extending from the core, which pass freely throughholes in the base and are provided at their ends above the base withnuts 2|. Around the portion of each of the screws 20 below the base isis a compression spring 22 which urges the base into engagement with thenuts 2|. By turning these nuts, the base can be adjustably moved alongthe axis of the electromagnet. Enclosing the space above theelectromagnet is a cap 23, through the top wall of which there extend thleads 24 of the electromagnet coil winding l6 which pass throughopenings in the core I5 andbase II.

On the base I! is a pair of U-shaped permanent magnets 25-26 which arearranged in a, single horizontal plane with the free ends of theirrespective side arms in adjacent relation. The magnets are secured tothe base by a pair of rectangular posts 21-28 (Fig. 4) which areinterposed between the adjacent ends of the side arms of the magnets inabutting relation thereto and are provided with enlarged head portions29-30 for engagement with the top surfaces of the magnets; the postsbeing secured to the base by screws M (Fig. 3). The magnets 25-26 arearranged in opposing relation, i. e., the adjacent ends of the side armsof the magnets have the same polarity, as is indicated by the letters Nand S in Fig. 4. The posts 21-28 are of magnetic material, such as softiron, and their top surfaces thus form a pair of pole faces, marked Nand S, which are efl'ectively the common poles of the two magnets.Cooperable with the magnets, and positioned im-. mediately above andsubstantially parallel to the pole faces of posts 21-28, is an armature22 (Fig. 3) which is attached at its bent-up left-hand end to anapertured flexible metal strip or hinge 33 which is supported by anangle bracket 34 secured to the base is by screws 25. The armature 32,carries a switch arm 28 which cooperates with contact screws 31-38threaded respectively in brackets 38-40 secured to the base IS. Theswitch constituted by arm 38 and contacts 31-" is adapted to beconnected in circuit with apparatus, to be controlled in accordance withthe switch arm position, by connecting the leads of the apparatus to thebrackets 24, 38 and lo-no such connections being shown in Figs. 1-4. The

armature is normally held by the magnets in attracted position withrespect to the pole faces of posts 21-28 (so that the switch arm is inengagement with the lower contact screw 31) and is biased in a directionaway from the pole faces by the force of a tension spring 4| which istightly threaded at its lower end on screw 35 (Fig. 3) and is freelythreaded at its other end on a screw 42 which is a clearance fit in anopening through an extension 43 of the armature. By turning screw 42,the tension of spring 4| can be adjusted.

Connected to the upper end of the electromag-' net plunger I1 is a rod44 having at its top an enlarged portion or head 45, of soft iron, whichis a sliding fit within theereduced tubular upper portion 46 of anon-magnetic cup or liner 41 having at its mouth a flange 48 which isinterposed at its margin between the valve casing I I and the core ii.The liner 41 serves to shield the electromagnet and the magneticswitching device from the fluid controlled by the valve. as well as tomagnetically separate the upper portion of the plunger I! from the corel when the plunger is raised by energization of coil IS. The reducedupper portion 48 of the liner extends through central openings in thecore I! and base l9 and is of such length that its closed top end isapproximately flush with the pole faces of the posts 212l; the outerside surface of the portion 48 being in engagement with the innercorners 49 (Fig. 4) of the side arms of the magnets which are ground toconform thereto.

When plunger I! is raised by energization of its electromagnet, thesoft-iron head 45 of rod 44 is interposed between the polar ends of themagnets 252i so that the flux thereof is shunted by the head, theresultant reduction of magnetic attraction of the armature permittingthe force of its bias spring 4| to move it in a direction away from themagnets so that the switch arm 36 engages the upper contact screw 38.When, upon deenergization of the electromagnet, the head 45 isretracted, the armature returns to its attracted position as shown. Inthe structure of Figs. 1-4, the controlling function of the magneticswitching device does not appear, since the structure is intended merelyto illustrate the arrangement of the device with respect to typicalmeans for operating the shunting head 45. However, it is apparent thatthe switching device could be employed to control an electrical circuitincluding means, such as signal lights, for remotely indicating thecondition of the closure member of the valve. In some applications ofthe switching device, it is important that the armature be released orattracted when the shunt operating means reaches a particular point inits travel; for that reason, the base I 9 is arranged so that it can beraised or lowered (as has been described) to determine that point, itbeing understood that under normal bias of the armature the same isreleased when the shunting head 45 is inserted only partially betweenthe magnets. Referring now to the diagram of Fig. 5, the magneticswitching device, described in connection with Figs. 1-4, is shown insimplified form. It comprises a switch blade 60 which is biased by itsown resilience in an upward direction. Attached to the underside of theswitch blade is an armature 6| which cooperates with a single U-shapedpermanent magnet 82, the polar ends of which are marked N and S. Carriedby a solenoid plunger 63, having an energizing coil winding 64, is asoft-iron rod 85 which is arranged to project between the side arms ofthe magnet 62, when plunger 63 is in its raised position as shown, toshunt the flux of the magnet so that the armature assumes itsunattracted position wherein the switch bladeis in engagement with acontact element 66. Extending from the bottom of plunger 53 is a stem 41which, by w of example, is shown provided with a closure member 68cooperable with a valve seat 69. The lower portion of stem ll is reducedin diameter to provide a shoulder II with which an electromagneticlatching plunger ll cooperates. This plunger is biased toward the valvestem by a compression spring I! and is retractable therefrom uponenergization of its coil winding 11. The coil windings 44 and II areconnected at one of their ends to contacts 14 and 15, respectively,which are engageable by a manually-operable switching member Ii. The

other end of the main plunger winding 44 is connected to a contactelement 11 which is engageable by the switch blade 60 when the armatureBI is in its attracted position with respect to magnet 42; the other endof the latching plunger winding 13 being connected to the upper contactelement 8|. The switching member 16 is connected, in series with asource of electrical energy II, to ground; switch blade I also beinggrounded. Thus. when the switching member 18 is moved into engagementwith contact ll, current then flows through the latching plunger winding13 (contact element 44 being engaged by switch blade 80), therebyeflecting retraction of the latching plunger so that the main plunger 8!falls by gravity. In the downward movement of the main plunger, thesoftiron rod is removed from the field of magnet 62 so that armature Clis downwardly attracted, thereby effecting disengagement of switch blade60 from contact 44 so that the energizing circuit of the latchingplunger ll is broken and that plunger moves into engagement with theunreduced upper portion of stem 61. If thqswitching member is now movedback into engagement with contact I4, current flows through the winding64 of the main plunger (switch blade 4. now being in engagement withcontact element 1'!) and that plunger moves upwardly; the plunger Hbeing forced by its bias into latching position below shoulder 10 whenthe main plunger is near the end of its stroke. Slight continued upwardmovement of the main plunger eflects magnetic release of the armature,by shunting of the magnet flux by rod 65, so that the resultantseparation of the switch blade from contact 11 breaks the main plungercircuit: the parts assuming the positions shown in Fig. 5.

In Fig. 6. the main parts are identical with those of Fig. 5 and havetherefore been assigned the same reference numerals and need not furtherbe described. The chief difference lies in the provision of amomentary-contact manuallyoperable switching member 19 for controllingthe energizing circuits of the main and latching plunger coil windingsi4 and 13, so that it is not necessary to automatically break thesecircuits (as in Fig. 5) upon completion of the plunger stroke-theright-hand ends of the windings 64 and 13 leading directly to ground, asindicated. The magnetically operated switch The manual switching memberI! is biased by its own resilience to a neutral position out ofengagement with contacts 14 and I5. The parts are shown in the figure inthe positions assumed after the member 18 had momentarily been broughtinto engagement with contact 14 so that the main plunger 63 was raisedto its latched position, thereby effecting ma netic release of armature6| due to the shunting of magnet 62 by rod 65the condition of the mainplunger being indicated by the resultant energization of the circuit ofsignal light. If the lower contact I is now engaged by member 19, thelatching plunger II is retracted and the main plunger falls-theresultant downward attraction of armature 6| effecting deenergization ofsignal light 80 and energization'of the other light 8!.

In the arrangement of Fig. 7, the magnetic switching device is employedto control the lifting-coil circuit of a solenoid plunger 83 having alifting coil 84 and a holding coil 85. These coils are connectedtogether at one of their ends and to a contact 86 which is engageable bya manually-operable switching member 81 which is adapted to connect the,source 18 to the coils in common. The other end of the lifting coil 84is connectable to ground, through the contact 11 of the magneticswitching device, to complete its energizing circuit; the other end ofholding coil 85 being directly grounded. In the figure,

the plunger 83 is shown held in its raised position switching deviceassuming its attracted position with blade 60 in engagement with contact11. If the member 81 is then reclosed, both lifting and holding coilsare simultaneously energized and the plunger is raised, the circuit ofthe lifting coil 84 being automatically opened when the plungerapproaches the end of its stroke, due to release of blade 60 fromcontact 11; the continued energization of coil 85 then sufficing to holdthe plunger in its raised position.

While I have'herein shown and described a specific embodiment of myinvention, I wish it to be understood that modifications may be madewithout departing from the spirit of the invention, and that I intendtherefore to be limited only by the scope of the appended claims.

I claim as my invention:

1. In a magnetic control device: a U-shaped permanent magnet,flux-conducting means extending from each of the polar ends of the armsof said magnet in a. direction at right-angles to the plane of the armsof the magnet to form a pair of pole faces in a plane parallel to saidarms, a generally flat armature cooperable with the magnet and disposedin a plane substantially parallel to that of said pole faces, saidarmature normally being held by the magnet in attracted position withrespect to said pole faces and biased in a direction away from them, andmeans movable into a position between the side arms of the magnet for soshunting the flux thereof that the armature then moves under the forceof said bias.

2. In a magnetic control device: a U-shaped permanent magnet, agenerally flat armature that of of the magnet and adjacent one side ofsaid arms, said armature normally being held by the magnet in attractedposition with respect thereto and biased in adirection away from it, andmeans insertable between the arms of the magnet from the side thereofaway from the armature and movable in a direction at right-angles to thelane of said arms, said means when in inserted position being effectiveto so shunt the flux of the magnet that the armature then moves underthe force of said bias.

3. In a magnetic control device: a U-shaped permanent magnet,flux-conducting means extending from each of the polar ends of the armsof said magnet in a direction at right-angles to the plane of the armsof the magnet to form a pair of pole faces in a plane parallel to thatof said arms, a generally flat armature cooperable with the magnet anddisposed in a plane substantially parallel to that of said pole faces,said armature normally being held by the magnet in attracted positionwith respect to said pole faces and biased in a direction away fromthem, and means insertable between the arms of the magnet from the sidethereof away from the armature and movable in a direction atright-angles to the plane of said arms, said means when in insertedposition being effective to so shunt the flux of the magnet that thearmature then moves under the force of said bias.

4. In a magnetic control device: a pair of U- shaped permanent magnetsarranged in a single plane with the poles thereof in adjacent andmagnetically-opposed relation, a generally flat armature cooperable withsaid magnets and disposed in a plane substantially parallel to that ofthe arms of the magnets and adjacent one side of said arms, saidarmature normally being held by the magnets in attracted position withrespect thereto and biased in a direction away from them, and meansinsertable between the arms of the magnets from the side thereof awayfrom the armature and movable in a direction at rightangles tothe planeof said arms, said means when in inserted position beingeffective to soshunt the flux of the magnets that the armature then moves under theforce of said bias.

5. In a magnetic control device: a pair 01 U- shaped permanent magnetsarranged in a single plane with the poles thereof in adjacent andmagnetically-opposed relation, flux-conducting means interposedbetweeneach of the adjacent pairs of poles of said magnets and extendingat right-angles to the plane of the arms of the magnets to form a pairof pole faces in a plane parallel to that of said arms, a generally flatarmature cooperable with the magnets and disposed in a planesubstantially parallel to that of said pole faces, said armaturenormally being held by the magnets in attracted position with respect tosaid pole faces and biased in a direction away from them, and meansinsertable between the arms of the magnets from the side thereof awayfrom the armature and movable in a direction at right-angles to theplane of said arms, said means when in inserted position beingcooperable with said magnet and disposed in a effective to so shunt theflux of the magnets that the armature then moves under the force of saidbias.

6. In a magnetic control device: a pair of U- shaped permanent magnetsarranged in a single plane with the poles thereof in adjacent andmagnetically-opposed relation; flux-conducting means interposed betweeneach of the adjacent pairs of poles of said magnets and extending atright-angles to the plane or the arms 01 the magnets to form a pair ofpole faces in a plane parallel to that or said arms, a flat elongatedarmature cooperable with the magnets and disposed in a planesubstantially parallel to that of said pole faces, said armature beingpivoted at one end and lying transversely of the common axis of themagnets. said armature normally being held by the magnets in attractedposition with respect to said po1e faces and biased 10 in a directionaway from them, and means insertable between the arms of the magnetsfrom the side thereof away from the armature and movable in a directionat right-angles to the plane of said arms, said means when in insertedposition being efiective to so shunt the flux of the magnets that thearmature then moves under the force of said bias.

LEWIS L. CUNNINGHAM. go

8 amneucns crrnn The following references are of record in the me ofthis patent:

UNITED STATES PATENTS Number Number Germany June 17, 1922

